1. The Field of the Invention
This invention relates to a novel polymer having enhanced adhesion and resolution in patterning of a resist, and a resist composition containing the same. More particularly, this invention relates to a novel polymer applicable to the fabrication of a resist composition useful for micro process using a variety of radiations, including KrF excimer laser, ArF excimer laser, F2 excimer laser, X-ray, or e-beam, and a resist composition containing the polymer
2. Related Prior Art
With the progress of high-integration semiconductor devices, there has been a demand for an extra fine pattern of less than 0.10 micron in the manufacture of very LSI (Large-Scale Integration) semiconductor products. Hence, the exposure wavelength becomes much shorter than the wavelength of the conventional radiations, such as g- or i-beam, and researches on the lithography using far-ultraviolet radiation, KrF excimer laser, ArF excimer laser, F2 excimer laser, X-ray, and e-beam have recently drawn considerable attention. The light sources most spotlighted in the next-generation lithography requiring a pattern of less than 0.10 micron are ArF excimer laser and F2 excimer laser.
The resist composition includes a component having an acid-liable function(hereinafter, referred to as “polymer”), a component generating acids under irradiation(hereinafter, referred to as “photoacid generator”), a solvent, and in some cases, a dissolution inhibitor, or a basic additive.
The polymer used as a principal ingredient of the resist composition is supposed to contain functional groups having an adequate affinity to the developing solution, a high adhesion to the substrate, a high etch resistance, and a high resolution.
The specific examples of the functional groups may include hydroxyl groups, lactone groups, or carboxyl groups to enhance the affinity to the developing solution and the adhesion to the substrate, and norbornene derivatives or adamantane derivatives to enhance the etch resistance. However, the structure of the polymer is more important than a specific functional group in regard to enhancement of the resolution.
In an attempt to satisfy such properties, a number of copolymers have recently been developed, such as copolymers of adamantane acrylate and cyclolactone acrylate (see SPIE, Vol. 3049, pp. 519-25 (1997); or U.S. Pat. No. 6,013,416 (Nozaki, et al.)), a pure olefin copolymer (see SPIE, Vol;. 3049, pp. 92-99 (1997)), a hybrid copolymer of these monomers (see SPIE, Vol. 3049, pp. 84-91 (1997)), etc. However, these polymers are not still unsatisfactory in the aspect of the lithography performance.